Rotor



H. c. REIST' Oct. 16, 1928.

ROTOR Filed Jan. 13, 1928 InvenToP by [weak Hi5 ATTor'ne Patented Oct.16, 1928.

UNITED STATES HENRY G. REIST, OF

PATENT OFFICE.

COMPANY, A CORPORATION OF NEW YORK.

ROTOR.

Application file nuary 13, 1928- Serial No. 246,629.

My invention relates to rotors for dynamoelectric machines.

It has been the practice'heretofore in constructing rotors fordynamo-electric ma- 5 chines to rigidly connect the pole pieces and therim, to which they were secured, to the spokes or hub structure. Thecentrifugal force exerted on the pole pieces has made it necessary touse a heavy rim, and as this rim 1 was rigidly fastened to the hubstructure it has been difficult to-determine What portion of thestresses in the spokes have been due to centrifugal force. As a result,in designing these rotors the hub structure has been made much largerthan would be required to support the load of the magnetic structurebecause of the uncertainty in the centrifugal stresses to which it issubjected.

The primary object of my invention is toconstruct the rotor in suchmanner that the centrifugal stresses in the magnetic structure, whichincludes the rim and the pole pieces, will not be transmitted to the hubor other central supporting structure. I accomplish this by fasteningthe pole pieces to the rim or annular body and supporting the same on acentral supporting structure in such man nor that torque is transmittedfrom one to the other without transmitting centrifugal stresses from theannular body to the central supporting structure. In this way anyuncertainty in the design of the rotor is practically eliminated as theannular body resists the action of centrifugal force substantiallyaltogether by circumferential tension stresses therein, and the centralsupporting structure is only required to support the weight of themagnetic structure, withstand stresses due to vibration, and transmittorque between the annular body and the rotor shaft. These stresses aredeterminable in my improved construction with a fair degree of accuracy,and particularly those due to centrifugal force, which are the greatest,so that it is possible to obtain a much more satisfactory design than inprior constructions.

A further object of my invention is to provide a rotor constructionwhich can readily be fabricated of plates and suitable structural shaes.

y invention will be more fully set forth in the following descriptionreferring to the accompanying drawing and the features of novelty whichcharacterize my invention will be pointed out with particularityin theclaims annexed to and forming a part of this specification.

In the drawing, Fig. 1 is a fragmentary end view of my improved rotorpartly broken away; Fig. 2 is a transverse section on the line 2-2 ofFig. 1, and Fig. 3 is a perspective v ew of a portion of the rotor withthe pole pieces removed.

Referring to the drawing, the form of my improved rotor illustratedincludes a magnetic structure comprising pole pieces 10 and an annularbody 11 which is mounted on a central supporting structure secured tothe rotor shaft. The annular body 11 is made of a plurality of curvedoverlapping staggered plates 12 bolted together with the convex surfacesthereof outwardly presented so as to constitute the continuous annularbody 11 to which the pole pieces 10 are bolted at 10 In order to avoidany uncertainty in the distribution of centrifugal stresses between themagnetic structure and the central sup porting structure, the former ismounted on the latter so as to be movable radially outward therefromwhen its circumference is elongated under centrifugal stresses, but isprevented from rotating relative thereto. In this way, centrifugalstresses in the magnetic structure are resisted substantially altogetherby circumferential tension in the annular body 11 as there are noradially acting forces restricting the radial outward movement thereof.

The central supporting structure comprises a hub 13 and radiallyextending spokes 14 of I-shaped cross-section which .are arranged withtheir major axes extending axially of the rotor and secured to the hub13 by annular plates 15. These annular plates, which are bolted togetherat 15, are also bolted at 15 to flanges 13 formed on the hub 13 and at15 to the spokes 14. It is preferred to fabricate the spokes 14 ofsuitable plates 14 and 14 secured together by angles 14 and space blocks14 bolted thereto to form I- shaped sections, although other suitableforms of spokes may be em loyed.

The connection between t e spokes 14 and the annular body 11 whichtransmits torque between them without exerting radially acting forcesresisting the outward movement of the annular body when itscircumference elongates under the action of centrifugal force may be ofany suitable form but in the construction illustrated, it comprisesradially I slidab arranged pins '16 carried by the body 11 and y fittedin openings 17" formed in angle brackets l'i' which are bolted to theends of the spokes 14. The annular body 11 is firmly seated on thespokes by keys 11 which are arranged in key ways 17 b formed in theangle brackets 17.

It is apparent that centrifugal stresses in the magnetic structure willbe resisted substantially altogether by circumferential tension in theannular body 11 as there are no radially acting forces which resist theoutward movement of the'annular body relative to the central supportingstructure, the pins 16 transmitting torque only from one to the other.This makes it possible to determine the stresses in the rotor and designthe same with a reasonable factor of safety without the use of morematerial than actually required to withstand the stresses to which therotor is subjected.

By fabricating the rotor of plates and structural shapes as'abovedescribed, the use of patterns and castings is avoided and the rotor canfor this reason be cheaply and readily constructed.

Various modifications of my improved rotor will occur to those skilledin the art, so'that I do not wish to be limited to the particulararrangement shown and described except as set forth in the appendedclaims.

W at I claim as new and desireto secure by Letters Patent of the UnitedStates is:

1. A rotor for dynamo-electric machines having a central supportingstructure, a plurality of overlapping plates, connected together toconstitute a unitary annular body surrounding said central supportingstructure, a plurality of pole pieces secured to said annular body andmeans for forming a driving connection between said central supportingstructure and said annular body for guiding the latter in its movementawa from and toward the former under the actlon of centrifugal force sothat centrifugal force acting on said annular body will be resistedsubstantially altogether by tension stresses therein.

2. A rotor for dynamo-electric machines having a central supportingstructure, a plurality of curved overlapping plates having their convexsurfaces presented outwardly and connected together to constitute aunitary annular body surrounding said central supporting structure, aplurality of pole pieces secured to said annular body, and means forforming a driving connection between them and for guiding said annularbod in its movement away from and toward sai central supportingstructureunder the action of centrifugal force sothat centrifugal force acting onsaid annular body will be resisted substantially altogether by tensionstresses ing radially arranged pins slidably connecting said centralsupporting structure and said annular body for transmitting torque fromone to the other so that centrifugal forces acting on said annular bodywill be resisted substantially altogether by tension stresses therein.

4. A rotor for dynamo-electric machines having a central su portingstructure comprising spokes of I-s iaped cross-section With their majoraxes extending axially of the rotor, a plurality of overlapping platesconnected together to constitute a unitary annular body surrounding saidcentral supporting structure, a plurality of pole pieces secured to saidannular body, an means forming a driving connection between said centralsupporting structure and said annular body and or guiding the latter inits movement away from and toward the former under the action ofcentrifugal force so that centrifugal force acting on said annular bodywill be resisted substantially altogether by tension stresses therein.

5. A'rotor for dynamo-electric machines having a central su portingstructure comprising spokes of I- liaped cross-section with their majoraxes extending axially of the rotor, a plurality of overlapping platescon nected. together to constitute a unitary annular body surroundingsaid central supporting structure, a plurality of pole pieces secured tosaid annular body, and means including radially arranged plIlS slidablyconnecting said central supporting structure and said annular body fortransmitting torque from one to the other so that centrifugal forcesacting on said annular body will be resisted substantially altogether bytension stresses therein.

In witness whereof, I have hereunto set my hand this 10th day ofJanuary, 1928.

HENRY G. REIST.

